Non-Coplanar Volumetric Modulated Arc Therapy for Brain Tumours Using an O-Ring Gantry Linear Accelerator: A Dosimetric Evaluation

Purpose: This study evaluates the dosimetric advantages of Non-Coplanar Volumetric Modulated Arc Therapy (ncVMAT) over Coplanar Volumetric Modulated Arc Therapy (cVMAT) enabled by a novel O-ring gantry that permits couch rotation for Brain Tumours.

Methods: Fifteen patients with primary or metastatic brain tumors were retrospectively replanned using coplanar and non-coplanar VMAT techniques. All plans were generated for delivery on an Panacea Siddarth-II superia O-ring gantry linear accelerator. Dosimetric parameters including PTV coverage, conformity index (CI), homogeneity index (HI), gradient index (GI), doses to organs at risk (OARs), low-dose spillage, and normal brain integral dose were compared.

Results: Both techniques achieved equivalent target coverage. NC-VMAT significantly improved conformity and gradient indices while reducing maximum dose to the brainstem and optic apparatus. Normal brain V12Gy and V5Gy were reduced with NC-VMAT. Integral dose to uninvolved brain tissue was lower in the non-coplanar technique. Treatment time increased modestly due to couch rotation.

Conclusion: Non-coplanar VMAT delivered on an O-ring gantry linear accelerator is feasible and provides superior dose conformity and OAR sparing in selected brain tumor cases.

Dr. K. R. Muralidhar, MSc. Tech, Dip. R.P., M.Phil., PhD, FUICC (USA), MHA, IICA (ID), is the Director of Physics at Karakinos Healthcare Private Limited. He has over 29 years of experience in the field, with 94 presentations and publications, 21 published papers, 61 presented papers, 11 international presentations and 141 citations with an h-index of 8.

He holds a PhD, M.Phil., and Diploma in R.P from BARC,, M.Sc., Tech from JNTU. He earned certification in Genomic technologies from university of London, Inside cancer certificate from University of BATH UK , MHA in International Business and Hospital Operations, He is also an IICA-certified Independent Director, with certifications in Environment, Social and Governance (ESG) from the World Development Corporation, Six Sigma Green Belt (Healthcare), Infection Control and Prevention Management, Quality Control Management, and Business Responsibility and Sustainability Reporting (BRSP).

Dr. Muralidhar’s have been recognized through several prestigious honors, including the “Jewel of India Award,” “Bharat Gaurav Puraskar,” and “Golden Aim” Award. He is also a recipient of the UICC Fellowship at M.D. Anderson Cancer Institute, Houston, Texas, USA, and the IAEA Fellowship in Vienna, Austria—awarded to him twice.